1. Field of the Invention
This invention relates generally to medical devices and, more particularly, to methods and apparatus for reducing post-surgical adhesions between living tissues and an implant introduced into a surgical site of a patient.
2. Description or Related Art
A major clinical problem relating to surgical procedures or inflammatory diseases can be unwanted tissue growth, or adhesion, which can occur during the initial phases of the healing process after surgery or disease. Another problem can be foreign body reactions in response to medical devices or implants introduced into a surgical site. Still another problem can be leakage, migration or diffusion of substances, for instance fluids, from an implant into surrounding tissues.
One approach to the problem of adhesion has been the use of bioresorbable barrier materials, in the form of gels, coatings, fabrics, foams, films, and the like, that are placed between a healing post-surgical site and adjacent surrounding tissue. Examples of such barrier materials can be found in U.S. Pat. No. 5,412,068 to Tang et al., U.S. Pat. No. 5,795,584 to Totakura, U.S. Pat. Nos. 6,034,140 and 6,133,325 to Schwartz et al., and U.S. Pat. No. 6,136,333 to Cohn et al., all of which are expressly incorporated herein by reference.
More specifically, the patent to Tang et al. discloses films and other bioresorbable medical devices formed from polycarbonate fibers. The patent to Totakura discloses surgical adhesion barriers comprising copolymers and/or block copolymers derived from trimethylene carbonate. The patents to Schwartz et al. disclose anti-adhesion membranes made of carboxyl-containing polysaccharides and polyethers. The patent to Cohn et al. discloses polymeric anti-adhesion compositions comprising poly(ester)/poly(oxyalkylene) ABA triblocks or AB diblocks. Similarly, the problem of foreign body reactions has been addressed by applying biocompatible polymeric coatings to medical devices, such as, for instance, stents. An exemplary method for coating a stent is disclosed in U.S. Pat. No. 6,153,252 to Hossainy et al., also expressly incorporated herein by reference.
Unfortunately, the coatings and other barriers discussed above have met with only limited success. For instance, some of the prior art barrier materials may be resorbed into the body too quickly, yielding undesirable drops in local pH levels, which may cause or exacerbate such problems as local inflammation, discomfort and/or foreign antibody responses. Other materials may take too long to resorb, may be insufficiently malleable, or may require complex chemical formulations and/or reactions which can increase the cost of manufacturing.